Systems which convert between color video signals and grey scale video signals are known in the art, as are systems employing digitally encoded video information, such as disclosed, by way of example, in U.S. Pat. Nos. 4,233,601; 4,345,276; 4,437,093; 4,373,156; 4,232,311; 4,368,484; 4,481,509; 4,481,594; 4,425,581; and 4,270,125. However, none of these prior art systems known to applicants is readily capable of use in systems where it is desired to inexpensively transmit computer generated color video information great distances over single coaxial cables to RGB type of monitors, such as normally employed with computer displays, such as an IBM PC. Moreover, no such systems are known to applicants which transmit both color and black and white video information in the same multilevel grey scale code format for ultimate display on the same RGB monitor. Furthermore, in this regard, applicants are not aware of any prior art encoders or systems which employ a 16 level grey scale code, i.e. 16 levels or shades of grey, to encode the video signal into 16 possible R,G,B,I color combinations to provide the four R,G,B,I color bits over a single coaxial cable with no loss of bandwidth in an efficient and cost effective manner. In addition applicants are not aware of any prior art encoders or systems which employ a single converter to convert all four R,G,B,I bits into a common multilevel grey code for transmission over a single coaxial cable instead of requiring separate converters for each R,G,B, and I color intensity. These disadvantages of the prior art are overcome by the present invention.